The presence of radioactive gas .sup.222 Rn in water supplies of New England and elsewhere in the world has been known and reported since early in this century. Particularly high levels have been detected and measured in water supplies derived from granitic rock such as found in Maine and New Hampshire. Radon 222 and the various radon daughters enter the ground water by decay of naturally occurring uranium found in such granites. Recent studies express concern over possible correlation of high radon levels in water and air with excess cancers in the exposed population. See Radon-222 in Potable Water Supplies in Maine: The Geology, Hydrology, Physics & Health Effects by Charles T. Hess et al., Land & Water Resources Center, University of Maine, Orono, Maine 04773, September, 1979.
As the foregoing study points out, exposure to radon in water supplies is through two pathways. One is direct ingestion of the water. Second, because randon is only weakly dissolved and is easily given up by water as a gas, it may be inhaled after partitioning or separation of the radon into the air from radon enriched water. The University of Maine Land & Water Resources Center recommends that anyone with concentrations of radon greater than 10,000 pCi/l (pico Curies per liter) should take steps to use a different water supply, install radon removal equipment such as some type of aeration system, or provide adequate ventilation and air turnover in all high water use rooms.